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 * Copyright (C) 2017-2021 Apple Inc. All rights reserved.
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 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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#include "config.h"
#include "MarkStackMergingConstraint.h"

#include "GCSegmentedArrayInlines.h"
#include "JSCInlines.h"

namespace JSC {

MarkStackMergingConstraint::MarkStackMergingConstraint(Heap& heap)
    : MarkingConstraint("Msm", "Mark Stack Merging", ConstraintVolatility::GreyedByExecution)
    , m_heap(heap)
{
}

MarkStackMergingConstraint::~MarkStackMergingConstraint()
{
}

double MarkStackMergingConstraint::quickWorkEstimate(SlotVisitor&)
{
    return m_heap.m_mutatorMarkStack->size() + m_heap.m_raceMarkStack->size();
}

void MarkStackMergingConstraint::prepareToExecuteImpl(const AbstractLocker&, AbstractSlotVisitor& visitor)
{
    // Logging the work here ensures that the constraint solver knows that it doesn't need to produce
    // anymore work.
    size_t size = m_heap.m_mutatorMarkStack->size() + m_heap.m_raceMarkStack->size();
    visitor.addToVisitCount(size);
    
    dataLogIf(Options::logGC(), "(", size, ")");
}

template<typename Visitor>
void MarkStackMergingConstraint::executeImplImpl(Visitor& visitor)
{
    // We want to skip this constraint for the GC verifier because:
    // 1. There should be no mutator marking action between the End phase and verifyGC().
    //    Hence, we can ignore these stacks.
    // 2. The End phase explictly calls iterateExecutingAndCompilingCodeBlocks()
    //    to add executing CodeBlocks to m_heap.m_mutatorMarkStack. We want to
    //    leave those unperturbed.
    if (m_heap.m_isMarkingForGCVerifier)
        return;

    m_heap.m_mutatorMarkStack->transferTo(visitor.mutatorMarkStack());
    m_heap.m_raceMarkStack->transferTo(visitor.mutatorMarkStack());
}

void MarkStackMergingConstraint::executeImpl(AbstractSlotVisitor& visitor) { executeImplImpl(visitor); }
void MarkStackMergingConstraint::executeImpl(SlotVisitor& visitor) { executeImplImpl(visitor); }

} // namespace JSC